Antioxidant and Cytotoxic Phenolic Compounds of Areca Nut(Areca catechu)
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CHEM.RES.CHINESE UNIVERSITIES 2010,26(1),161—164 Antioxidant and Cytotoxic Phenolic Compounds of Areca Nut(Areca catech u)
ZHANG Xing,WU Jiao,HAN Zhuang,MEI Wen—li and DAI Hao.fu Key Laboratory ofTropical Crop Bioteehnology,Ministry ofAgriculture,Institute ofTropical Bioscience and Biotechnology,Chinese Academy ofTropicalAgricultural Sciences,Haikou 571101. R.China
Keywords Areca catechu;Phenylpropanoid;DPPH;Antioxidant activity;Cytotoxic activity Article ID 1005--9040(2010)--O1—-161--04
1 lntroduction Areca catechu L.(Palmae),commonly known as all jmportant economical seed crop.js widely culti. vated in tropical and subtropical areas,including India, Southeast Asia,East Africa and New Guinea.Areca nut(frequently known as bete1 nut)is the ripe fruit of the tree A.catechu.Areca nut can be chewed and it is a common masticatory in tropical and subtropical countries.It was estimated in the early 1990s that 10% t0 20%of the world’s population chewed beteI quid daily “.Areca nut is commonly used in folklore medi. cine for treatment of various diseases such as dyspep- sia,constipation,beriberi and oedema.It’s reported mat the areca nut ofA.catechu possesses anthelmintic. anti—inflammatory,antioxidant[ psychoactive【3'4】, antidepressant{51.anti-H1V-1 t6】effects and so on.Are. ca nut contains 50%一60%sugars. 1 5%lipids (glyceride of laurie,myristic and oleic acid),1 5% condensed tannins(phlobatannin,catechin),polyphe- nolics(NPF.86 .NPF.86IB.NPF.861IA and NPF一 86IIB) and 0.2%一0-3%alkaloids(arecoline.arecai. dine.guvacine and guvacoline) .Although a lot of literatureL '6 showed that areca nut had a strong anti. oxidant activity,no exact component contributing the antioxidant activity to areca nut has been reported vet. During the course of our searching for antioxidant genus from tropical medicinal plants,l1 phenolic compounds possessing antioxidant activity were iso. 1ated by bioassay.guided fractionation from tIle EtoAc fraction of areca nut.which exhibited consi. derable antioxidant activity bv DPPH assay in our preliminary test.This paper describes the structural determination of these compounds,their antioxidant activities by DPPH assay,and cytotoxic activity by MTT method. 2 MateriaI and Methods 2.1 General Procedure Al1 melting points were determined with a Bej— jing Taike X--5 melting point apparatus and were un・- corrected.Optica1 rotations were measured with a Rudolph Autopol Ill digital polarimeter.The UV spectra and DPPH radica1.scavenging assay were measured and carried out on a Beckman DU800 spec- 打ometeL IR spectra were determined on a Nicolet 380 FTIR spec仃ometer.The H and”C NMR spectra were recorded on a Bruker AV.400 N Ⅱ spectrometer The chemical shifls were given on scale with TMS as an internal standard,and coupling constant(J)was expressed in Hz.The MS data was recorded on API Qstar—Pulsar and VG-Auto—Spec一3000 spectrometers. MTT Radical-scavenging assay was performed on a Microplate reader(EL ̄800,Bio・Tek Company).
2.2 Chemical and Reagents DPPH and ascorbic acid(Sigma1 were used for test antioxidant activity,The eell lines SGC.790 1 (human gastric cancer)and SMMC-772 1(human liver cancer)were obtained from the Cell Bank of Type Culture Collection of Shanghai Institute of Cell Biology,Chinese Academy of Sciences.Commercial silical gel(Qingdao Haiyang Chemistry Group Co., 200—300 and 60—80 mesh)was used for column chromatography.Precoated silical gel(Qingdao Haiyang Chemistry Group Co.)was used for analyti・ cal TLC.Sephadex LH一20(25—1 00 gm,Merck)was
Corresponding author.E-mail:hfdai@yahoo.cn;meiwenli@yahoo.corl1.cn Received December 23,2008;accepted January 1 3,2009. Supported by the National Programs for Science and Technology Development of China(No.2007B 1 27B04) 162 CHEM.RES.CHINESE UNⅣERSITIES Vlo1.26
used for column chromatography
2.3 Plant Material The areca nut of A.catechu was collected from Ding’an Cotmty,Hainan Province.China.jn March 2006.and identified by associate Professor DAI Zheng.fu of Institute of Tropical Bioscience and Bio— technology,Chinese Academy of Tropical Agricultural Sciences where a voucher specimen(BL200603061 was deposited.
2.4 Extraction and lsolation The freshly milled areca nut of A.catechu(39.7 kg)was exhaustively extracted with 95%EtOH at room temperature.After evaporation,the residue was suspended in water and partitioned with light petro- leum,EtOAc and,2-BuOH successively.The crude extracts of the petroleum.EtOAc and -BuOH ffac- tions showed SCs0 values(SC50 value was extrapolated from the liner regression analysis and denoted the concentration of sample required to scavenge 50%of DPPH radicals)of>100,27.6 and 85.1 lxg/mL,by DPPH assay,respectively.The result suggests that the antioxidants were mainly contained in the EtOAc fraction,which further investigation was focused on. The EtOAc fraction(2 1.6 g)was subjected to column chromatography over silical gel eluted with CHCl .MeOH gradients(volume ratio 50:1 to 0:1)to obtain 7 fractions(A 1一A7).Repeated column chro— matography on silica gel chromatography eluted with petroleum ether-acetone gradients(4:l一2:1.volume ratio1 and Sephadex LH.20(95%EtOH),led to the isolation ofcompounds 1(11.9 rag),2(5.4 mg),a(16.6 mg)and 9(13.6 mg)from A1(2.5 g).Fraction A2(4.3 g) was subjected to Sephadex LH一20 and thcn subjected to silica gel chromatography to yield compounds s(20.0 rag),6(19.0 mg),7(3.1 rag)and 11(11.6 rag). Fraction A3(3.4 g)was subjected to Sephadex LH一20 (95%EtOH)to yield compounds 4(18.2 mg)and 8(16.1 mg).Ad6.3 g)was subjected to silica gel chromatography eluted with CHCI3一MeOH(20:l一5:1. volume ratio)to yield compound lo(1 1.6 mg). H1CO 2.5 DPPH Radical—scavenging Assay The DPPH assay was performed as described[ . In this assay,ascorbic acid was used as positive con— trol,a 0.1 mmol/L solution of DPPH(1,1-diphenyl一2一 picrylhydrazy1)in methanol was prepared and to 2 mL of mis solution was added 0.1 mL of the antioxidant solution in methano1 at different concentrations r 1.56一l 00 ̄tg/mL).The reaction mixtures were in・ cubated at room temperature for 30 rain.After incuba- tion,the absorbance was read at 517 nm,and mean value was obtained from three duplicated readings. Scavenging activity was determined by the follow equation:scavenging activity(%)=【 0nlTol—AsamDle)/ contr0l】×100%. 2.6 Cytotoxic Activity Assay The human gastric cancer eell line(SGC.790 l、 and human liver cancer(SMMC一772 1、were main. tained in RPMI.1 640 supplemented with l 0%fetaI bovine serum(FBS).1 00 units/mL penicillin and l 00 gg/mL streptomycin sulfate at 37。C.5%Co,.The MTT assay was performed according to the method described in the previous literature【 J.